Armature for induction-motors



(No Model.)

' A. L. CUSHMAN.

ARMATURB FOR INDUCTION MOTORS.

Patented Mar. 3,

inOenror Witnesses UNITED STATES PATENT OFFICE.

ABE L. CUSIIMAN, OF CONCORD, NEWV HAMPSHIRE.

ARMATURE FOR INDUCTION-MOTORS.

SPECIFICATION forming part of Letters Patent No. 555,899, dated March 3, 1896. Application filed June 24, 1895. Serial No. 553,774. (No model.)

To all whom it may concern.-

Be it known that I, ABE L. CUsHMAN, a citizen of the United States, residing at Concord, in the county of Merrimac and State of New Hampshire, have invented certain new and useful Improvements in Armature WVindings; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The objects of this invention are, first, to provide a good starting-torque, and, second, to simplify and cheapen the construction of induction-motors.

I employ a laminated core having grooyes formed longitudinally in its periphery, in which are placed copper bars which project slightly beyond the ends of said core, the ends of the bars being connected in pairs, each pair when so connected forming a short-circuit rectangle; and my invention consists essentially in the arrangement of these shortcircuit rectangle coils upon the armature successively insets, whereby each set shall form an irregular figure, as fully set forth in the following specification and claims and clearly illustrated in the accompanying drawings, forming a part thereof, of which Figure 1 represents my improved armature in end elevation, in which one set of my improved coils are shown in full lines, while the remaining coils, as well as the field-magnets, are shown in dotted lines. Fig. 2 is a detached view showing one complete coil or short-circuit rectangle in perspective. Fig. 3 is a detail showing one of the end connections.

A is an arbor upon which are mounted the collars B, having radial arms Z7, which carry the laminated core C. This core C is grooved longitudinally, as at c, for the reception of copper bars D, which project far enough beyond the laminated core C to be connected one with another by wires or bars E, as shown.

The number of copper bars D which I may use depends wholly upon the number of poles in the field-magnet to which my improved armature is to be applied. For example, in Fig. l I show in dotted lines four fie1d-magnets F, which require an armature having a core provided with forty-two slots, each containing a bar D, having their ends connected in pairs by the bars E, and to carry my invention into effect I commence anywhere say, for instance, at the bar Dand connect both its ends with the bar-D and D would likewise be connected with bar D and so on, counting off eleven bars or slots each time in connecting each pair, causing each set to more than cover the periphery of said core. This is clearly illustrated in Fig. l, in which I show the end connections of one complete set of short-circuit rectangle coils in full lines and lettered E E E E the bar E being seen to cross under the bar E and attach to a bar D, which is the fifth from the bar D, to which one end of the end connection E is attached, said coils thus forming an irregular figure, each occupying a different position in relation to the field-magnets, which greatly e11- hances the starting-torque.

In effecting one of the objects of my inventionviz., that of simplicity and cheapness the end connections form an important feature. In Figs. 2 and 3 these connections E are shown in detail. A flat piece of copper is first cut in the form seen in Fig. 3, it being a little over one-half the required length and about twice the required width. Then the strip is cut centrally and longitudinally, dividing it for most of its length, as seen at e, the divided portions being bent in opposite directions at the point indicated by a dotted line in Fig. 3, leaving the whole end 6 to proj ect at a right angle and forming the oifsets 6 as seen in Fig.2, the ends of the bar E thus formed being then inserted in slots d formed for the purpose in the ends of the coil bars D and soldered or otherwise secured therein.

It is obvious that to determine the number of bars D or grooves C to be used in my improved armature it is only necessary to select a number which isnot evenly divisible by the number of poles of the armature, thus pro ducing unsymmetrical polarities.

Having described my invention, what I claim is- 1. In an alternating-current induction-motor, an armature-winding composed of coils each of which forms a short-circuit rectangle,

ICO

4:. In an armature for alternating-current induction-motors, a slotted core, coils or wind ings forming a short-circuit rectangle resting in said slots, the said slots being too few in number to cause a set of coils to form a regular polarity upon the periphery of the armature.

In testimony whereof I affix my signature in presence of tWo witnesses.

ABE L. OUSI-IMAN. Witnesses:

J. B. THURSTON, B. G. RYDER. 

